Metal Spinning

IQS Newsroom Articles on Metal Spinning

About Metal Spinning and Metal Spinning Services Including: Aluminum Spinning, CNC Metal Spinning, Copper Spinning, Flow Forming, Hydroforming, Metal Spinners, Shear Spinning, Sheet Metal Spinning, Spin Forming, Stainless Steel Spinning, Tank Heads & Titanium Spinning.

Metal spinning, often called spin forming, is a cold worked metal fabrication technique that uses a flat round disc of sheet metal which rotates on a spinning lathe. A metal spinner applies pressure to the rotating blank using several tools to shape the metal over a form called a mandrel. This pressure can be applied by a single tool or by multiple levers. The finished product should have no wrinkling or warble due to the high speed of rotation around the mandrel. The process is quick and cost efficient. An average metal piece will only take from 5 to 10 minutes, and to change the spinning shape, one must only replace the mandrel. This process uses sheets of various kinds of metals, including aluminum, titanium, stainless steel and copper, which are in performed shapes or go through sheet metal spinning to become products used in the aerospace, food processing, filtration, medical, military, pharmaceutical and pulp and paper industries. Engine parts, nozzles, tank heads, funnels, freezers, mixing bowls, filter housings, pressure vessels, cartridges and cyclones are all produced by a form of metal spinning. Metal spinning can be done by hand, but a CNC metal spinning machine, or computer numeric controlled machine, usually produces metal spun products. Flow forming is a popular alternative of spin forming, an advanced process that allows variation in wall thickness of the product. Tube spinning, which produces cylinder shapes, and shear spinning, which produces cone or contoured shapes, are the 2 forms of flow forming. To obtain products with uniform thickness, hydroforming is a type of metal spinning that uses fluid pressure to form metal into a shape.

Metal spinning is a cost-effective choice for forming metal, usually used for smaller runs. But when spinning can't meet more complex design specifications, flow forming is often used. It's the main alternative to standard metal spinning, and flow forming produces hollow, symmetrical shapes by using rollers to extrude a cross-sectional area of wall thickness of a pre-formed metal part, often called a blank or perform. The thickness of the part is determined by the gap that is maintained between the mandrel and the rollers. This gap may change, to produce a product with inconsistent or uniform wall thickness. The end product parts are round in cross section, but may be straight sided cones or contoured shapes. The metal which is worked into a shape is either preformed by welding or in sheet form. Heat resistant steels such as stainless steel are good materials for the flow forming process, because their ductility and tensile strength are ideal for cold extrusion. Flow forming is able to create seamless, single pieces that have a wide range of design flexibility with increased tensile strength.

Tube forming, a flow forming method, takes tubular performs and cold works them via rollers and a mandrel to produce a tube with uniform or variable wall thickness. When shapes are made with one closed end (like a vessel), the bottom of the perform rests against the face of the mandrel while the material is moved in the same direction as the rollers. This is called forward flow forming. Reverse flow forming is a technique that produces a part with two open ends (like a tube). The force applied by rollers pushes against a serrated ring at the end of the mandrel, which compresses and extrudes the material. Shear spinning, the second method of flow forming, produces cone-shaped metal products by a flat blank that is sheared by rollers over a rotating mandrel. The diameter of the blank doesn't change, but the thickness decreases depending on the angle of the mandrel. No material is lost in this process. Hydroforming is an alternative to standard metal spinning and flow forming. In this cost-effective process, the metal flows around a punch instead of being stretched with dyes by using high pressure hydraulic system to create parts with more consistent thickness. There are 4 types of hydroforming. The most common type, tube hydroforming, is generally performed at low pressure and produces tubular parts with high integrity and structural performance. Panel hydroforming is a high pressure process that manufactures products for the automotive and aerospace industry. The third type, low pressure hydroforming, involves reshaping tubes when the cross-section definition is not strict. High pressure hydroforming also reshapes the tube more severely than any other form. In this type of hydroforming, the length-to-circumference ratio can change up to 50 percent.

When using metal spinning to fabricate a product, it is important to note the supplier's output capability. Some metal spinning manufacturers are not capable of short run orders and may have limitations as to the diameter and thickness of final product desired. However, many suppliers offer sizes from a fraction of an inch to over 6 feet in diameter. Sometimes, a metal spinning manufacturer will only have the capacity to spin a certain type of metal, such as stainless steel or aluminum. Though not all manufacturers can offer every type of spinning service, metal spinning can mean lower tooling costs because spinner dies are simpler and cheaper. Spinning tooling can also be made in-house by many spinning shops, meaning shorter lead times. The spinning process often work-hardens the metal product as it is being shaped, providing a stronger end product. The metal spinning business continues to grow as the process becomes better through technological advances.

Metal Spinning and Metal Spinning Services Images Provided by Acme Metal Spinning, Inc.

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Types of Metal Spinning

• Aluminum metal spinning fabricates metal parts by rotating aluminum sheet metal on a spinning lathe.
• CNC machine spinners (computer numerical controlled) and related technology are most often used during the metal spinning process. Today's modern CNC technology has made it possible to produce high volume, close tolerance, concentric metal parts quickly and economically. CNC machine spinners are also used for the fabrication of other sheet metal parts.
  
• Custom metal spinners are what the majority of metal spinning shops use. Because of flexible rapid tooling and the short set up times associated with the technique, the costs of metal spinning can be much lower than other metal fabrication techniques.
  
• Hand metal spinners are still used by some manufacturers but are increasingly rare. The spinning of the metal is machine controlled but the appliance of pressure is done by hand, making for a very hard and cumbersome process; the results sometimes lack uniformity from piece to piece.
  
• Hydroforming is a tool and die process that uses hydraulic fluid to make components, often for the automotive industry.
• Metal spinners rotate metal circles.
• Stainless steel spinning is the most prominent type done by metal spinning shops. Most, however, are capable of spinning a wide range of common to exotic metals, including aluminum, brass, copper, hastelloy and titanium.
  
• Tank heads are circular, pressed ends to cylindrical tanks.
  
• Titanium spinning is a way to create light yet strong spun products that are resistant to corrosion and offer a lustrous appearance.

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Metal Spinning Terms

Alloy - A substance that has metallic properties and is composed of two or more chemical elements of which at least one is an elemental metal.
 
Buckling - An uncontrolled deformation pattern perpendicular to the surface of a sheet caused by compressive stresses.
 
CNC - Computer Numeric Controlled.
 
Camber - The sheering tendency of sheet metal material which occurs via the bending of the same plane.
 
Cold Working - The reforming of metal usually, but not necessarily, conducted at room temperature.  Also referred to as cold forming or cold forging. Contrast with hot working.
 
Concentric - Having the same center, as concentric circles; having the same axis, as concentric cylinders.
 
Deep Drawing - The drawing of deeply recessed parts from sheet material through plastic flow of the material when, the depth of the recess equals or exceeds the minimum part width.
 
Die - A tool, usually containing a cavity, that imparts shape to solid, molten, or powdered metal primarily because of the shape of the tool itself. 
 
Draw Plate - A circular plate with a hole in the center contoured to fit a forming punch; used to support the blank during the forming cycle.
 
Elongation - The amount of permanent extension of the material before it fractures. 
 
Hemming - The bending of a piece 180 usually done in two steps after a piece has been created via spinning. First a sharp angle is created then closed via a flat punch and die.
 
Hold Down - A device used to secure a workpiece.
 
Lathe - Machine tool for shaping metal or wood; the workpiece turns about a horizontal axis against a fixed tool.
 
Mandrel - A tapered steel form used to support metal as it is being formed. Also called a Chuck.
 
Necking - The reduction of the cross-sectional area of metal in a localized area by uni-axial tension or by stretching.
 
Orange Peel - Texture of steel that appears like an orange, either from the steel mill or after forming.
 
Overbending - Bending metal a greater amount than called for in the finished piece to allow for springback.
 
Reset - The realigning or adjusting of dies or tools during a production run; not to be confused with the operation setup that occurs before a production run.
 
Stamp - This is a general term used to describe most press workings.
 
Support Plate - Used most often as a spacer within the spinning machine.
 
Tooling - The form to which the sheet metal is formed to simulate.

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Metal Spinning from Wikipedia, the free encyclopedia

Metal spinning, also known as spin forming or spinning, is a metalworking process by which a disc or tube of metal is rotated at high speed and formed into an axially symmetric part. Spinning can be performed by hand or by a CNC lathe.

Metal spinning ranges from an artisan's specialty to the most advantageous way to form round metal parts for commercial applications. Artisans use the process to produce architectural detail, specialty lighting, decorative household goods and urns. Commercial applications include rocket nose cones, cookware, gas cylinders, brass instrument bells, and public waste receptacles. Virtually any ductile metal may be formed, from aluminum or stainless steel, to high-strength, high-temperature alloys. The diameter and depth of formed parts are limited only by the size of the equipment available.

A brass vase spun by hand. Mounted to the lathe spindle is the mandrel for the body of the vase a shell sits on the "T" rest. The foreground shows the mandrel for the base. Behind the finished vase are the spinning tools used to shape the metal.

Process

The spinning process is fairly simple. A mandrel, also known as a form, is mounted in the drive section of a lathe. A pre-sized metal disk is then clamped against the mandrel by a pressure pad, which is attached to the tailstock. The mandrel and workpiece are then rotated together at high speeds. A localized force is then applied to the workpiece to cause it to flow over the mandrel. The force is usually applied via various levered tools. Simple workpieces are just removed from the mandrel, but more complex shapes may require a multi-piece mandrel. Extremely complex shapes can be spun over ice forms, which then melt away after spinning. Because the final diameter of the workpiece is always less than the starting diameter the workpiece must thicken, elongated radially, or buckle circumferentially.

A more involved process, known as reducing or necking, allows a spun workpiece to include reentrant geometries. If surface finish and form are not critical, then the workpiece is "spun on air"; no mandrel is used. If the finish or form is critical then an eccentrically mounted mandrel is used.

Tools

The basic hand metal spinning tool is called a spoon, though many other tools (be they commercially produced, ad hoc, or improvised) can be used to effect varied results. Spinning tools can be made of hardened steel for using with aluminum or solid brass for spinning stainless steel or mild steel.

Some metal spinning tools are allowed to spin on bearings during the forming process. This reduces friction and heating of the tool, extending tool life and improving surface finish. Rotating tools may also be coated with thin film of ceramic to prolong tool life. Rotating tools are commonly used during CNC metal spinning operations.

Commercially, rollers mounted on the end of levers are generally used to form the material down to the mandrel in both hand spinning and CNC metal spinning. Rollers vary in diameter and thickness depending on the intended use. The wider the roller the smoother the surface of the spinning; the thinner rollers can be used to form smaller radii.
Cutting of the metal is done by hand held cutters, often foot long hollow bars with tool steel shaped/sharpened files attached. In CNC applications, traditional carbide or tool steel cut-off tools are used.

The mandrel does not incur excessive forces, as found in other metalworking processes, so it can be made from wood, plastic, or ice. For hard materials or high volume use, the mandrel is usually made of metal.

Advantages & Disadvantages

Several operations can be performed in one set-up. Work pieces may have re-entrant profiles and the profile in relation to the center line virtually unrestricted.

Forming parameters and part geometry can be altered quickly, at less cost than traditional metal forming techniques. Tooling and production costs are also comparatively low. Spin forming is easily automated and an effective production method for prototypes as well as high production runs.

Other methods of forming round metal parts include hydroforming, stamping and forging or casting. Hydroforming and stamping generally have a higher fixed cost, but a lower variable cost than metal spinning. Forging or casting have a comparable fixed cost, but generally a higher variable cost. As machinery for commercial applications has improved, parts are being spun with thicker materials in excess of 1" thick steel. Conventional spinning also wastes a considerably smaller amount of material than other methods.

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